Piston grinding machine



July 3, 1951 c. J. GREEN PISTON GRINDING MACHINE 3 Sheets-Sheet 1 Filed June 15, 1950 w 40 a w m w/fif 2 i w, P h NF r NW N a km N w Cl Nw I ii a 6M July 3, 1951 Filed June 13, 1950 C. J. GREEN PISTON GRINDING MACHINE 3 Sheets-Sheet 2 fitter-mg July 3, 1951 c. J. GREEN PISTON GRINDING MACHINE 3 Sheets-Sheet 3 Filed June 13, 1950 This invention relates to Patented July 3, 1951 2,559,534 rrsron GRINDING MACI:

' Clarence J. Green,

Norton Company,

Worcester, Mass., assignor to Worcester, Mass., a corporation of Massachusetts Application June 13, 1950, Serial No. 167,768

4 Claims. 1

The invention relates to grinding machines and more particularly to a grinding machine for grinding irregular shapes such as tapered oval surfaces on automotive pistons and the like. a machine of the type disclosed in my pending application, Serial No. 84,659, filed March 31, 1949.

One object of the invention is to provide a simple and thoroughly practical grinding machine for grinding tapered oval or elliptical shapes on automotive pistons. Another object of the invention is to provide a piston grinding machine having a rock bar and a master cam and follower roller which are arranged to produce tapered oval or elliptical shapes onaworkpiece. Another object of the invention is to provide a cam type grinding machine for generating predetermined tapered contours on the periphery of a piston. Another object of the invention is to provide a piston grinding machine having a pivotally mounted rock bar which is oscillated during grinding by means of a master cam and follower roller in which one end of the workpiece to be ground is supported by the master cam spindle while the other end of the workpiece is rotatably supported on a fixed axis to facilitate generating an irregular shape which tapers from one end to the other. A further object of the invention is to provide a footstock which is pivotally mounted for adjustmcnt about the pivotal axis of the rock bar. Anl other object is to provide a footstock having a rotatable spindle which supports a workholder and work driver and to provide a driving mechanism for synchronously rotating the master cam spindle and the footstock spindle. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction. combinations of elements, and arrangements of parts, as will be exemplifled in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which is shown one of various possible embodiments of the mechanical features of this invention,

Fig. 1 is a front elevation of a grinding machine embodying the invention;

Fig. 2 is a vertical sectional view, on an enlarged scale, through the footstock;

Fig. 3 is a fragmentary plan view of the actuating mechanism for the -footstock;

Fig. 4 is a fragmentary plan view of the machine, on an enlarged scale, showing the work supporting and driving mechanism;

Fig. 5 is a sectional view, taken approximately on the line 5-5 of Fig. 4, showing the work driving mechanism;

Fig. 6 is a sectional view, taken approximately on the line 6-8 of Fig. 4, showing a portion of the work driving mechanism;

Fig. 7 is 'a fragmentary horizontal sectional view, on an enlarged scale, showing the work supporting arrangement together with the master cam and follower roller;

Fig. 8 is a fragmentary cross-sectional view, on an enlarged scale, taken approximately on the line 8-8 of Fig. 1; and

Fig. 9 is a diagrammatic view showing the arrangement of the parts set-up for grinding tapered ovals on pistons being ground.

A grinding machine has been illustrated in the drawings comprising a base H] which supports a longitudinally movable worktable II on the usual flat and V-ways (not shown). The table II serves as a support for a cam grinding unit l2 which will be hereinafter described. The table II may be traversed longitudinally relative to the base In to facilitate positioning the workpiece being ground for a grinding operation b3? means of a manually operable traverse mechanism comprising a hand traverse wheel l3. The traverse wheel I3 is connected to rotate a gear M which meshes with a gear l5 mounted on a m tatableshaft IS. The shaft l6 also supports a gear l1 which meshes with a rack bar l8 depending from the underside of the worktable II. It will be readily apparent from the foregoing disclosure that a manual rotation of the traverse wheel I 3 will .be imparted through the rack and gear mechanism above described to produce a longitudinal traversing movement of the table II. The direction of rotation of the traverse wheel l3 serves to determine the direction or movement of the table I I. This mechanism is substantially the same as that disclosed in the expired U. S. Patent to C. H. Norton, No. 762,838, dated June 14, 1904, to which references may be had for details of disclosure not contained herein.

The table II, if desired, may be reciprocated longitudinally by a power operated mechanism such as that shown in the prior patent above referred to. This mechanism may comprise a power driven shaft l9 which is driven by means of a multiple speed drive contained within the casing 20. The rotatable shaft [9 is connected into a reversing clutch (not shown) which is actuated by means of a reversing lever 2| to reciprocate the table II longitudinally. The

. within a belt guard 30with reversing lever 2| is automatically actuated by means of a pair of adjustable table dogs 22 and 23 which are adiustably supported in a T-slot 24 formed in the front edge of the table II.

A rotatable grinding wheel 25 is mounted on one end of a rotatable wheel spindle 25. The wheel spindle 26 isjournalled in spindle bearings (not shown) supported .within a transversely movable wheel slide 2 The wheel slide 21 is arranged to be adjus" dtransversely on the usual flat and V-ways (not shown) formed on the upper surface of the base ill. The grinding wheel 25 may be driven by any suitable means, such as for example, an electric motor 23 mounted on the upper surface of the wheel slide 21. The motor 28 is provided with an armature shaft 29'which ls connected by means of a multiple V-belt drive (not shown) contained the wheel spindle 26.

In order to facilitate a precise transverse adjustment of thewheel slide 2|, a suitable feeding mechanism is provided comprising a manually operable feed wheel 3| which is mounted on the front of the machine base It and is operatively connected to rotate a feed screw (not shown) to cause the grinding wheel 25 and the wheel slide 21 to move transversely toward and from the table I. The direction of movement of the wheel slide 21 being determined by the direction of rotation of the feed wheel 3|. In the construction illustrated in the drawings, the feed wheel 3| may be actuated either manually or automatically as desired. A mechanically actuated feed pawl 32 which is actuated by and in timed relation with the movement of the reversing lever 2| as the table II is reciprocated, serves automatically to advance the grinding wheel 25 at the ends of the reciprocatory stroke of the table II. This mechanism is substantially identical with that shown in the prior U. S. patent, to which reference may be had for details of disclosure not contained herein.

A cam grinding unit I2 is mounted on the upper surface of the table II. The unit |2 serves as a support for a rock bar 36. The rock bar 36 is provided at its opposite ends with a pair of spaced axially aligned trunnions 31 and 38 which are rotatably supported by a pair of spaced brackets 39. and 40 fixedly mounted on the upper surface of the unit l2. The rock bar 36 supports a rotatable master cam spindle 42 in a pair of spaced bearings 43 and 44. The

- 4 same amount of relief. It is therefore desirable in grinding certain pistons that a tapered oval shapebe produced on the piston with the short axis of the oval lying in a plane passing through the axis of the bosses 58 and 59 to allow this portion of the piston to expand to a greater extent when'heated during normal use.

Itis desirable to provide a suitable mechanism for moving the rock bar 3B'to an inoperative position to facilitate loading and unloading of pistons or workpieces into the machine. This mechanism may comprise a tension spring 60 (Fig. 8) one end of which is fastened to a stud 5| which is adjustably mounted on the headstock unit 4|. The other end of the spring 60 is connected to a stud 52 which is carried by an arm 53 fixedly mounted on the rock bar 36. It willv be readily apparent from the foregoing disclosure that the spring 60 serves normally to maintain the master cam 5| in operative engagement with the follower roller 52. The stud 6| is preferably provided with a threaded portion 61 having a nut 68, by means of which the tension of the spring 60 may be varied as desired.

In order to facilitate separating the master cam 5| from the followerroller 52, a cam 64 is fixedly mounted on a shaft 65 which is journalled in a suitable bearing formed in the headstock unit M. A manually operable lever 66 is mounted on the outer end of the shaft 65 by means of which the'cam 64 may be rotated to engage a follower stud 69 adjustably mounted on the bracket 63. When it is desired to separate the master cam 5| from the follower roller 52, the control lever 66 is rocked to rotate the cam 64 into engagement with the follower stud 69 and thereafter to rock the rock bar 35 in a counterclockwise direction (Fig. 8) to separate the master cam 5| from the follower roller 52.

In order to obtain one of the objects of this invention, it is desirable to provide a footstock 10 which is arranged so that it may be adjusted about the axis of the rock bar as a pivot to facilitate setting up the machine and also to provide master cam spindle 42 is provided with a work 1 supporting center 45 which is arranged to support the left-hand end of a workpiece, such as a piston 45. A rotatable drive shaft 41 is provided with a sprocket 48 which is connected by means ofa link chain 49 withja sprocket 50 mounted on the left-hand end of the master cam spindle 42. The master cam spindle 42 is provided with a master cam 5| which is arranged to engage a rotatable follower roller 52. The follower roller 52 is supported on a rotatable shaft 53 which is iournalled in spaced bearings 54 and 55 which are fixedly mounted on the unit- |2.

In the grinding of automotive pistons, such as, some of the aluminum alloy and other alloy pistons, it is desirable to grind a relief on the sides of the piston adjacent to the thickened boss portions 58 and 53 (Fig. 7) due to the fact that when the piston becomes heated during use, this portion of the piston expands greater than the lower and cylindrical portions thereof. The portions of the piston at right angles to the plane of the bosses 58 and 59 is a relatively thin cylindrical portion and therefore does not need the the footstock with a work supporting member to engage and positively rotate the right-hand end of the workpiecev such as the piston 46 about a fixed axis while the headstock end of the workpiece isrocked transversely due to the shape of the master cam 5| so as to generate a predetermined tapered oval shape on the piston 46.

The footstock 10 is provided with a rotatable sleeve H which is rotatably journalled in a pair of spaced bearings 12 and 13 fixedly mounted within the footstock 10. A hollow spindle I4 is slidably keyed within the rotatable sleeve I l. The

hollow spindle 14 is provided with a central bore which supports a work supporting spindle 16. The work supporting spindle 15 is slidably keyed within the central bore 15 and is provided at its left-hand end (Fig. 2) with a work supporting plate 11 which is shaped to support and center the open end of the piston 46 to be ground. The spindle 16 also supports a yoke-shaped driver 18 which is arranged to engage a pin 89 passing through the wrist pin holes formed in the bosses 58 and 59. The work spindle 16 is provided with a reduced portion or rod 19 on its right-hand end (Fig. 2) which passes through a hole formed within the hollow spindle I4. A compression spring 8| surrounds the rod 80 and is interposed between a shoulder formed between the within the hollow spindle 14.

spindle I6 and the rod 80 and a shoulder formed A collar 82 is mounted adjacent to the right-hand end of the rod 80. A nut 83 is screw threaded onto the rod 80 by means of which the collar 02 may be ad- .iusted longitudinally relative to the rod 80. .The collar 82 serves to limit the movement of the spindle I6 toward the left under the influence of the compression of the spring 8 I.

In order to facilitate positively rotating the sleeve II in synchronism with the master cam spindle 42, the drive shaft 41 is arranged in alignment with the pivotal axis of the rock bar 36 and passes through a longitudinal bore formed within the rock bar 36. A sprocket 84 is mounted on the right-hand end of shaft 41 (Fig. 1) and is connected by means of a link chain 85 with a sprocket 86 mounted on the right-hand end of the rotatable sleeve II. It will be readily apparent from the foregoing disclosure that rotation of the shaft 41 will be transmitted through the link chain drive to rotate the sleeve II, the hollow spindle 14, the work' spindle I6, the work supporting plate 11 and the yoke-shaped driver I8 whereby rotating the piston 46 in synchronism with the rotation of the master cam spindle 42.

A suitable mechanism is provided for withdrawing the hollow spindle I4, the work spindle I6, the work supporting plate I1, and the yokeshaped driver plate I8 to facilitate loading and unloading pistons 46 into the machine. This mechanism may comprise a manually operable control lever 90 which is mounted on the upper end of a rotatable stud 9|. The stud 9| is rotatably supported in a bracket 92 whichis fixedly mounted on the upper surface of the footstock I0. An arm 93 is formed integral with the control lever 90 and is provided with a downwardly extending stud 84 carrying a rotatable roller 95 at its lower end. The roller 95 rides in an annular groove 96 formed in the hollow spindle 14. It will be readily apparent that by movement of the control lever 90,| the hollow spindle I4 together with the work supporting spindle I6 may be moved toward the right (Fig. 2) to an inoperative position to facilitate a loading and unloading operation. The compression spring BI is arranged to yieldably maintain the work supporting plate I1 in supporting engagement with the open end of the piston 46 during a grinding operation.

The footstock I0 is arranged for a transverse adjustment to facilitate setting up the machine. In the preferred form the footstock is arranged for a pivotal adjustment to pivot about the pivotal axis of the rock bar 36. As illustrated in Fig. II the bracket 40 which is fixedly mounted on the unit I2 is provided with a cylindrical portion 91 the axis of which is aligned with the axis of the rock'bar 36. The footstock I0 is provided with a cylindrical bore which mates with the cylindrical surface 91. Binder screws 98 (only one of which is shown in the drawings) are provided for locking the footstock in adjusted position relative to the bracket 40. It will be readily apparent from the foregoing disclosure that by loosening the clamping screw 98 the footstock I0 may be pivotally adjusted in a transverse direction.

A suitable driving mechanism is provided for synchronously rotating the master cam spindle 42 and the footstock spindle 16. The drive shaft 41 is connected by means of a universal joint I00 with a multiple V-groove pulley IN. The pulley IOI is supported on anti-friction bearings I02 which are fixedly mounted relative to the table II. A motor I03 is supported on a bracket I04 onthe table II. The motor I03 is provided meshes with a worm gear shaft I I2.

with an armature shaft I06 which is connected to rotat a worm I08 (Fig. 5). The worm I06 I01 keyed on a rotatable shaft I 08. The shaft I08 also supports a gear I09 which meshes with a gear IIO fixedly mounted on a rotatable clutch member III. The clutch member III is rotatably supported on a It is desirable to provide a multiple speed drive for the piston 46. This is preferably accomplished by providing a second gear train comprising a gear II3 which is keyed on the shaft I08. The gear I I3 meshes with a gear I I4 which is keyed on a rotatable clutch member I I5. The clutch member H5 is also rotatably supported on the shaft II2. A slidably mounted clutch member II6 (Fig. 6) is slidably keyed on the shaft H2 and is arranged to be shifted longitudinally relative thereto by means of a manually operable lever II 1 into engagement with either the clutch member I I I or the clutch member II5 depending upon the speed of rotation desired. The shaft H2 is provided with a multiple V-grooved pulley II8 which is connected by multiple V-belts with the multiple V-groove pulley IOI so that the rotative power of the motor I03 will be transmitted through the gear mechanism above described to rotate the shaft 41 and thereby synchronously rotate the master cam spindle 42 and the footstock spindle I6.

The operation of the improved grinding machine will be readily apparent from the foregoing disclosure. Assuming all of the parts have been previously adjusted and a master cam 5| of the desired contour is mounted on the master cam spindle 42, a workpiece such as the piston 46 is placed in supporting engagement with the footstock supporting plate 11 with the yoke-shaped driver I8 in engagement with a pin passing through the wrist pin after which the lever is moved to shift the spindle I6 toward the left so that the left-hand end of the piston 46 moves into supporting engagement with the center 45. If it is desired to grind a tapered oval shape tapering toward the left (Fig. 7) on the piston.

46, the low point of the master cam 5| is rotated into operative engagement with the master cam follower roller 52 after which the footstock I0 is adjusted so that the axis of the footstock spindle I6 is aligned with the master cam spindle 42. The machine may then be set in motion and the piston 46 will be rotated with the right-hand end thereof remaining concentric the axis of the spindle I6 and the left-hand end thereof oscillated as controlled by the shape of the master cam 5I on the piston being ground. In this setup of the machine the master cam spindle 42 moves from position 42 to broken-line position-42a, as diagrammatically indicated in Fig. 9.

If it is desired to produce a taper in the op-- posite direction, that is tapering toward the right, the master cam spindle 42 is rotated so that the high point of the master cam is in engagement with the follower roller 52. While in this position, the footstock I0 is transversely adjusted so that the axis of the footstock spindle I6 is aligned with the axis of the master cam spindle 42 when the master cam spindle 42 is in position 421). After this adjustment has been made, the footstock I0 is locked in adjusted position and a grinding operation performed during which the master cam spindle 42 shifts between the position 42b and position 42a as shown in broken-lines in Fig. 9. With this setup a tapered to generate the desired oval shape various objects hereinbefore set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a piston grinding machine having a transversely movable rotatable grinding wheel, a worktable, a rock bar pivotally supported on saidtable, a master cam spindle on said rock bar, means including a master cam on said spindle and a follower roller to impart a rocking movement to said rock bar. means including a work supporting center on said spindle to support one end of a workpiece to be ground, an adjustably mounted footstock on said table, a rotatable spindle on said footstock, a work supporting and a work driving member thereon, means to adjust said footstock transversely so that the axis of the footstock spindle is aligned with the axis of the master cam spindle when the low point of the master cam is in engagement with the follower roller so that the end of the workpiece adjacent to the footstock rotates about a substantially fixed axis while the other end of the workpiece rotates with the master cam spindle and is rocked away from and toward the grinding wheel as controlled by the master cam to generate a variable relief on the workvpiece, and means including a drive shaft synchronously to rotate the master cam spindle and the footstock spindle so as to synchronize rotation of the master cam and the workpiece.

2. In a piston grindin machine having a transversely movable rotatable grinding wheel,

a worktable, a rock bar pivotally supported on said table, a rotatable master cam spindle on said rock bar, means including a master cam on said spindle and a follower roller to impart a controlled rocking movement to said rock bar,

to be ground, a rootstock plvotally mounted on said table, a rotatable spindle on said footstock. a work supporting and a work driving member on said latter spindle, means to adjust the footstock about its pivotal axis so that the axis of the footstock spindle-ls aligned with the axis of the master cam spindle when the low point of the master cam is in engagement with the follower roller so that the end of the workpiece adjacent to the footstock rotates about a substantially fixed'axis while the other end of the workpiece rotates and is rocked toward and from the grinding wheel a controlled by the master cam to generate a predetermined tapered oval shape on the workpiece, and means including a drive shaft synchronously to rotate said master cam spindle and the footstock spindle tosynchronize rotation of the master cam and the workpiece.

3. In a piston grinding machine as claimed in claim 2, in combination with the parts and features therein specified in which the drive shaft passes through an axial bore in the rock bar, and synchronous driving connections between said shaft and the master cam spindle and between said shaft and the footstock spindle synchronmeans including a work supporting center on 7 said spindle to support one end of a workpiece ously to rotate the master cam and the workpiece.

4. In a piston grinding machine as claimed in claim 2, in combination with the parts and features therein specified in which the drive shaft passes through an axial bore coinciding with the pivotal axis of the rock bar, and synchronous driving connections including a link chain drive between said shaft and the master cam spindle, and an independent link chain drive between said shaft and the rootstock spindle synchronously to rotate the master cam and the workpiece.

CLARENCE J. GREEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

